Eco tire

ABSTRACT

An earth-friendly tire using raw materials derived from non-petroleum resources instead of all or part of raw materials derived from petroleum resources currently used for tires. The tire is prepared by using a natural rubber instead of a synthetic rubber; an inorganic filler and/or a biofiller instead of carbon black; vegetable oil instead of petroleum oil; and natural fiber instead of synthetic fiber so that the tire has a non-petroleum raw material in an amount of at least 75 % by weight based on the total weight of the tire.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a 37 C.F.R. § 1.53(b) divisional of U.S.application Ser. No. 10/226,144 filed Aug. 23, 2002, which claimspriority on Japanese Application No. 2001-254608 filed Aug. 24, 2001.The contents of each of these applications is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

The present invention relates to an eco tire comprising raw materialsderived from non-petroleum resources.

More than half of the whole weight of a tire on the market today is madeof raw materials derived from petroleum resources. For example, a commonradial tire for automobiles is made of about 20% by weight of asynthetic rubber, about 20% by weight of carbon black based on the totalweight of a tire, and other components such as an aromatic oil and asynthetic fiber, which means that such a tire contains more than 50% ofpetroleum raw materials based on the total weight.

However, it seems that there is a limit for using raw materials derivedfrom petroleum resources considering recent serious interests toecological problems and CO₂ emission control, as well as forecastedrising of petroleum price caused by limited reserve and decliningproduction of petroleum.

In view of the above problems, an object of the present invention is toprovide an eco tire by using raw materials derived from non-petroleumresources instead of all or part of conventional raw materials for tirederived from petroleum resources.

SUMMARY OF THE INVENTION

That is, the present invention relates to a tire comprising a rawmaterial derived from non-petroleum resources in an amount of at least75% by weight based on the total weight of the tire.

It is preferable to use a natural rubber, an inorganic filler and/orbiofiller, a vegetable oil, and a natural fiber as raw materials derivedfrom non-petroleum resources.

DETAILED DESCRIPTION

More than half of the whole weight of a tire on the market today is madeof raw materials derived from petroleum resources. For example,synthetic rubbers used as a rubber component, such as styrene-butadienerubber (SBR), butadiene rubber (BR) and butyl rubber (IIR) are preparedby polymerizing the monomers extracted from the C₄ fractions obtained bynaphtha cracking of crude petroleum. Carbon black used as a filler isprepared by atomization and heat decomposition of crude petroleum underatmosphere where bunker oil is burned. Petroleum oils used as a processoil, such as aromatic oil, naphthene oil and paraffin oil are heavy oilcomponents obtained by atmospheric distillation of crude petroleum.Polyester, a synthetic fiber used for case cord and others, is preparedby polycondensation of ethylene glycol with dimethyl terephtalate orterephthalic acid, where ethylene glycol is obtained from ethylene anddimethyl terephtalate or terephthalic acid is obtained from paraxylene,both ethylene and paraxylene being refined from crude petroleum. Waxes,antioxidants, resins, adhesives and vulcanization accelerators are alsoprepared from petroleum resources.

According to the present invention, an eco-tire (ecology-conscious tire)comprising at least 75% by weight, preferably at least 85% by weight,and more preferably at least 95% by weight of non-petroleum rawmaterials is achieved by using non-petroleum raw materials instead ofpetroleum raw materials such as synthetic rubbers, carbon black,petroleum oils and synthetic fibers. When the amount of thenon-petroleum raw materials is less than 75% by weight, effect ofreducing the consumption of petroleum resources remains small. Amongpetroleum raw materials, synthetic rubber and carbon black are maincomponents of a tire, and thus it is preferable to use non-petroleum rawmaterials instead of these components. Analyzed part by part, treadcontains petroleum raw materials the most, which amounts to about 23% ofthe whole weight of a tire. Then, side wall, case topping, inner liner,breaker topping and bead follow in order, and therefore it is preferableto use non-petroleum raw materials instead of petroleum raw materials inthese parts. Herein, examples of raw materials derived fromnon-petroleum resources include vegetable resources, minerals, coal,natural gas, shells, eggshell, crushed bone and crustacean shells.

Examples of non-petroleum raw materials used instead of synthetic rubberare a natural rubber and a modified natural rubber obtained by modifyinga natural rubber. It is preferable that at least 75% by weight, furtherat least 85% by weight of synthetic rubber is replaced by naturalrubber. When the replacement by natural rubber is less than 75% byweight, effect of reducing the consumption of petroleum resourcesremains small and rolling resistance tends to increase.

Examples of non-petroleum raw materials used instead of carbon black areinorganic fillers such as silica, sericite, calcium carbonate, clay,alumina, talc, magnesium carbonate, aluminium hydroxide, magnesiumhydroxide, magnesium oxide and titanium oxide; and biofillers includingvegetable polysaccharides such as starch and cellulose and animalpolysaccharides such as chitin and chitosan. Among them, silica ispreferable in order to ensure the reinforcement of rubber.

When silica is used, it is preferable that silica has a BET specificsurface area of 150 to 250 m²/g. When the BET specific surface area ofsilica is less than 150 m²/g, reinforcing property tends to be inferior.When the BET specific surface area of silica is more than 250 m²/g,there is a tendency that dispersibility is inferior, agglomeration iscaused and thus a tire has decreased physical properties.

It is preferable that at least 75% by weight, further at least 85% byweight of carbon black is replaced by an inorganic filler and/or abiofiller. When the total amount of the inorganic filler and thebiofiller is less than 75% by weight, effect of reducing the consumptionof petroleum resources remains small and rolling resistance tends toincrease.

When the inorganic filler is used instead of carbon black, it ispreferable to use a silane coupling agent together. There is noparticular limit for the kind of silane coupling agent as long as it iscurrently used in the field of production of tires. Examples of silanecoupling agents are bis(3-triethoxysilylpropyl)tetrasulfide,bis(3-trimethoxysilylpropyl)tetrasulfide,bis(2-triethoxysilylpropyl)tetrasulfide, 3-mercaptopropyltriethoxysilanand 2-mercaptoethyltrimethoxysilane. These silane coupling agents may beused alone or in any combination. Among them,bis(3-triethoxysilylpropyl)tetrasulfide and3-mercaptopropyltriethoxysilan are preferable from the viewpoint ofreinforcing property and processability, andbis(3-triethoxysilylpropyl)tetrasulfide is particularly preferable fromthe viewpoint of processability.

When silane coupling agent is used together with an inorganic filler, itis preferable to use 3 to 20% by weight of silane coupling agent basedon the inorganic filler. When the amount of silane coupling agent isless than 3% by weight, the effect of adding silane coupling agent isinsufficient. When the amount of silane coupling agent is more than 20%by weight, the effect to be obtained remains small in spite of costincrease.

Examples of non-petroleum raw materials used instead of petroleum oilsinclude vegetable oils such as castor oil, cotton seed oil, linseed oil,rape seed oil, soya bean oil, palm oil, coconut oil, arachis oil, rosin,pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesameoil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojobaoil, macadamia nut oil, safflower oil and tung oil. Among them, rapeseed oil, palm oil and coconut oil are preferable from the viewpoint oftheir supply, price and softening effect.

Among these vegetable oils, preferable examples are oils having lowunsaturation degree, such as semi-drying oils having an iodine number of100 to 130, and non-drying oil or solid oil having an iodine number ofat most 100. Herein, the iodine number is defined as the amount ofiodine based on gram, which can be absorbed by 100 g of oil. When theiodine number of the oil is more than 130, there is a tendency that tanδ is increased and hardness is decreased to cause increase of rollingresistance and decrease of steering stability.

It is preferable that at least 75% by weight, further at least 85% byweight of petroleum oil is replaced by vegetable oil. When the amount ofvegetable oil is less than 75% by weight, effect of reducing theconsumption of petroleum resources remains small and rolling resistancetends to increase.

It is preferable to blend vegetable oil so that the hardness of rubberbecomes 40 to 90 after vulcanization. When the hardness of rubber isless than 40, there is a tendency that required rigidity cannot beachieved. When the hardness of rubber is more than 90, processabilitytends to be inferior.

Examples of non-petroleum raw materials used instead of synthetic fiberinclude rayon and acetate which are made from wood pulp, and cupro whichis made from cotton seed crude linter. Among them, rayon is preferablebecause of its high strength required for a tire.

The tire of the present invention can be prepared according to aconventional method, but non-petroleum raw materials is used instead ofall or part of the petroleum raw materials which has been used so far.

EXAMPLES

The present invention is explained in detail based on Examples below,but not limited thereto. “Part(s)” and “%” in the following examplesmean “part(s) by weight” and “% by weight”, respectively, unlessotherwise specified.

Materials used in Examples and Comparative Examples are summarizedbelow.

[Raw Materials Derived from Petroleum Resources]

-   SBR: SBR1502 available from Sumitomo Chemical Co., Ltd.-   BR: BR150B available from Ube Industries, Ltd.-   IIR: C1-IIR1068 available from Exxon Chemical Japan Ltd.-   Carbon black (ISAF): Diablack I available from Mitsubishi Chemical    Corporation-   Carbon black (FEF): Diablack E available from Mitsubishi Chemical    Corporation-   Carbon black (GPF): Diablack G available from Mitsubishi Chemical    Corporation-   Carbon black (HAF): Diablack HA available from Mitsubishi Chemical    Corporation-   Carbon black (LM-HAF): Diablack LH available from Mitsubishi    Chemical Corporation-   Aromatic oil: Process X-140 available from Japan Energy Corporation-   Mineral oil: Diana Process PA32 available from Idemitsu Kosan Co.,    Ltd.-   Wax: Ozoace 0355 available from Nippon Seiro Co., Ltd.-   Antioxidant: Antigen 6C available from Sumitomo Chemical Co., Ltd.-   Cured resin: Sumilite resin PR12686 available from Sumitomo Bakelite    Co., Ltd.-   Adhesive (COST): COST-F available from Japan Energy Corporation-   Adhesive (S.620): Sumicanol 620 available from Sumitomo Chemical    Co., Ltd.-   Vulcanization Accelerator: Nocceler NS available from Ohuchi Shinko    Kagaku Kogyo Co., Ltd.    [Raw Materials Derived from Non-Petroleum Resources]-   Natural rubber: RSS#3-   Silica: Ultrasil VN3 available from Degussa Hules Co.-   Coupling Agent: Si-69 available from Degussa Hules Co.-   Sericite: KM-S available from Nippon Forum Co., Ltd.-   Calcium carbonate: Hakuenka CC available from SHIRAISHI KOGYO KAISHA    LTD.-   Vegetable oil: Purified palm oil J(S) available from Nisshin Oil    Mills, Ltd.-   Stearic Acid: Stearic acid Tsubaki available from NOF Corporation-   Zinc oxide: Zinc Oxide available from Mitsui Mining and Smelting    Co., Ltd.-   Sulfur: powdery sulfur available from Tsurumi Chemicals Co., Ltd.

Example 1

Kneading was carried out according to compounds listed in Table 1, andtread A (40% of the tire weight), side wall A (17% of the tire weight),inner liner A (8% of the tire weight), clinch apex A (3% of the tireweight), bead apex A (5% of the tire weight), breaker topping A (8% ofthe tire weight) and carcass ply topping A (3% of the tire weight) wereformed. Steel cord (8% of the tire weight) was used for the breaker, andcord (5% of the tire weight) made of 1840 dtex/2 rayon was used for thecarcass ply.

An unvulcanized tire was prepared by assembling the above components andother parts (3% of the tire weight) on a tire forming machine in a usualmanner, and the tire was heated and pressed in a vulcanizing machine toobtain an eco-tire comprising 97% by weight of non-petroleum rawmaterials (tire size: 195/65R15 91S).

Comparative Example 1

Kneading was carried out according to compounds listed in Table 1, andtread B, side wall B, inner liner B, clinch apex B, bead apex B, breakerB and carcass ply B were formed. A conventional tire comprising 44% ofnon-petroleum raw materials was prepared in the same manner as inExample 1 except that a cord made of 1670 dtex/2 polyester was used forthe carcass ply.

The tires prepared in Example and Comparative Example were subjected tothe following durability test and performance evaluations.

1) High Speed Durability

Evaluation of high speed durability was carried out in accordance withJIS D4230 “tire for automobiles” S range high speed durability test A.

2) Rolling Resistance Coefficient (RRC)

Rolling resistance was measured under the condition of speed of 80 km/h,air pressure of 250 kPa and load of 4.0 kN. Rolling resistancecoefficient was obtained by dividing the rolling resistance value withthe load value, and multiplying the result by 10⁴. The smaller thecoefficient is, the lower and the more excellent the heat build-upcharacteristic is.

3) Braking Test

Friction coefficient μ was determined from the brake stopping distance,which was measured by stopping the automobile mounted with the preparedtire, running at a speed of 100 km/h on dry asphalt road and wet asphaltroad. The friction coefficient μ is represented as an index to the μvalue of Comparative Example 1 as 100.

4) Evaluation Test on Real Automobile

Grip, rigidity and riding comfort characteristics were evaluated byusing a real automobile with an engine size of 2000 cc, which wasmounted with the prepared tire and run on dry asphalt road and wetasphalt road in a test course. The results are represented in scorebased on the value of Comparative Example 1 as 6. The higher the scoreis, the better the properties are. Only well-trained drivers can detectthe score difference of 0.5 point.

The results are shown in Table 2. Table 2 shows that the eco-tire ofExample 1 has smaller rolling resistance, better fuel consumption andequally excellent high speed durability and other properties comparedwith the conventional tire of Comparative Example 1. TABLE 2 Test Ex. 1Com. Ex. 1 High speed durability Passed Passed RRC 80 91 Braking testDry μ (index) 90 100 Wet μ (index) 90 100 Organoleptic test onautomobile Dry grip (score) 5.5 6 Wet grip (score) 5.5 6 Rigidity(score) 5.5 6 Riding comfort (score) 5.5 6

According to the present invention, a new and earth-friendly tire inanticipation of decline of petroleum supply can be prepared by using anatural rubber instead of a synthetic rubber, an inorganic filler and/ora biofiller instead of carbon black, vegetable oil instead of petroleumoil, and natural fiber instead of synthetic fiber so that the tirecomprises a non-petroleum raw materials in an amount of at least 75% byweight based on the total weight of the tire.

1. A tire comprising a raw material derived from a non-petroleumresource in an amount of at least 75% by weight based on the totalweight of said tire.
 2. The tire of claim 1, wherein the raw materialderived from a non-petroleum resource comprises a natural rubber.
 3. Thetire of claim 1, wherein the raw material derived from a non-petroleumresource comprises an inorganic filler, a biofiller, or an inorganicfiller and biofiller.
 4. The tire of claim 1, wherein the raw materialderived from a non-petroleum resource comprises a vegetable oil.
 5. Thetire of claim 1, wherein the raw material derived from a non-petroleumresource comprises a natural fiber.